低和高X射线状态下的TeV二进制HESS J0632 +057
The TeV binary HESS J0632+057 in the low and high X-ray state
摘要：
我们报告了2011年2月在X射线和TeV活动的高状态下对发射高质量X射线的HESS J 0632 +057进行的40 ks Chandra观测。我们利用ACIS-S相机在连续时钟模式下搜索了该系统中可能存在的X射线脉冲星。此外，我们比较了在这种高状态下的源的发射，其X射线的性质在低状态下的发射，捕捉到的47 ksXMM-牛顿观测2007年9月。我们没有发现任何周期或准周期信号在任何两个观察。我们推导出了平均脉冲分数3sigma上限的周期性信号的存在下，在低和高的发射状态，分别为~35%和25%（虽然这个限制是强烈依赖于频率和能带）。使用迄今为止HESS J 0632 +057的最佳X射线光谱，我们发现了低和高X射线发射态之间显著光谱变化的证据，吸收值和光子指数在Nh ~ 2.1-4.3x10^{21} cm^{-2}和Gamma ~ 1.18-1.61之间变化。与在其他TeV双星中观察到的不同，在这个源中，通量越高，X射线谱就越软。
英文摘要：
We report on a 40ks Chandra observation of the TeV emitting high mass X-ray binary HESS J0632+057 performed in February 2011 during a high-state of X-ray and TeV activity. We have used the ACIS-S camera in Continuos Clocking mode to search for a possible X-ray pulsar in this system. Furthermore, we compare the emission of the source during this high state, with its X-ray properties during a low state of emission, caught by a 47ks XMM-Newton observation on September 2007. We did not find any periodic or quasi-periodic signal in any of the two observations. We derived an average pulsed fraction 3sigma upper limit for the presence of a periodic signal of ~35% and 25% during the low and high emission state, respectively (although this limit is strongly dependent on the frequency and the energy band). Using the best X-ray spectra derived to date for HESS J0632+057, we found evidence for a significant spectral change between the low and high X-ray emission states, with the absorption value and the photon index varying between Nh ~ 2.1-4.3x10^{21} cm^{-2} and Gamma ~ 1.18-1.61. At variance with what observed in other TeV binaries, it seems that in this source the higher the flux the softer the X-ray spectrum.
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